1. Field of the Invention
The present invention relates to a fastener feeding mechanism for feeding fasteners from a fastener support rail formed in a magazine of a fastener driving device.
2. Description of the Prior Art
Japanese Utility Model Publication No. 55-28455 discloses a fastener driving mechanism in a fastener driving device. The fastener driving mechanism includes a slider and an engaging member. The slider is slidably movable relative to a magazine in a longitudinal direction of the magazine. The engaging member is pivotally mounted on the slider and includes an engaging portion for engagement with a row of fasteners disposed within a fastener support rail formed in the magazine in the longitudinal direction. The engaging member further includes a knob for operation by an operator with his hand. With this fastener driving mechanism, the loading operation of new fasteners into the fastener support rail is performed as follows:
Firstly, the operator moves the knob to pivot the engaging member in such a manner that the engaging portion moves away from the fastener support rail. Keeping the engaging portion in this position, the operator moves the slider rearward of the magazine. New fasteners are subsequently loaded into the fastener support rail from rear of the magazine. Upon releasing the knob and the slider, the engaging portion returns to the position for engagement with the fasteners and the slider is moved forward, so that the engaging portion abuts on the rear end of the row of the new fasteners.
Japanese Patent Publication No. 2-17309 discloses a fastener feeding mechanism having a feeder slidably mounted on a magazine in a longitudinal direction. A claw lever is pivotally mounted on the feeder and includes a claw for engagement with a shank of a fastener, and a pull for operation of the claw lever. The claw includes a cam surface for cooperation with the shank of the fastener. A protruding member is provided at the rear portion of the magazine for protruding into and retracting from a fastener support rail formed within the magazine. With this fastener driving mechanism, the loading operation of new fasteners into the fastener support rail is performed as follows:
Firstly, the protruding member is retracted from the fastener support rail to permit loading of the new fasteners. After completion of loading of the new fasteners, the protruding member is protruded to abut on the end of the row of the new fasteners. The feeder is thereafter moved to reach a position rearward of the new fasteners. As the feeder is thus moved, the claw lever is rotated through cooperation of the cam surface and the shank of the fastener which is disposed at a most forward position of the row of the new fasteners, so that the claw of the claw lever is moved away from the fastener support rail. When the feeder reaches the position rearward of the new fasteners, the claw lever returns to its position for engagement with the rear end of the row of the new fasteners.
However, with the former fastener feeding mechanism, the loading operation is very difficult because it involves two different steps, one for rotation of the engaging member to move the engaging portion away from the fastener support rail and another for moving the slider in the rearward direction while keeping the engaging member at the rotated position.
Further, with the latter fastener feeding mechanism, although the claw of the claw lever can be moved away from the fastener support rail through rotation of the claw lever according to the rearward movement of the feeder, it is necessary to provide the protruding member to engage the rear end of the row of the new fasteners so as to permit such rotation of the claw lever. Further, it is necessary to move the protruding member away from the fastener support rail for loading new fasteners again. Therefore, the loading operation is also difficult.